1. Field of the Invention
This invention relates in general to a data storage systems, and more particularly to physical information and extensions file and a file system translator.
2. Description of Related Art
Computing systems frequently are provided with storage subsystems having multiple storage devices connected to the computing system central processor through a device controller. For example, some computing systems include a plurality of disk arrange into a disk array with parity and sparing. Parity refers to organizing data into parity groups such that each modification of disk data that involves a relatively small write operation requires a read old data, read old parity, write new data, write new parity sequence of operations often referred to as a read-modified-write sequence. Sparing refers to providing spare data blocks to be used in the event of a disk failure.
A disk array controller is provided between the disk array and a computing system. As applications running in the computing system requests blocks of data from the disk array, the disk array controller checks whether the requested data block is located in a cache memory or whether the requested data block is on the disk array.
However, the disk controller often does not enable an open system host to access data on the disk array. Some storage device controller provide a Small Computer Standard Interface (SCSI) interface for allowing open system hosts to access data on the storage devices through the storage device controller thereby allowing an open system host to use an Enterprise System Connection (ESCON) storage device as one of it's own storage devices. Another method is to provide an intermediary disk controller between the open systems host and the legacy disk controller to allow new host types to use legacy disk controllers and storage devices. Thus, these new controllers act as an intermediary between hosts and controller units. These intermediary controllers also provide additional caching.
However, the intermediary controller does not have any provision for data sharing, wherein an originating host normally uses ESCON to access the legacy disk controller that knows where data is stored on the storage device. An open system host connected to an intermediary controller via a SCSI port uses a different operating system than the originating host and therefore the different operating systems refer to and organize the data differently. Accordingly, users or administrators of the open system hosts are not able to identify where data really are or what the data really are from viewing the file system of the intermediary controller.
It can be seen that there is a need for a file translation system that allow a host computer to directly access data from a different host type without moving the actual data.
It can also be seen that there is a need for an apparatus and method that provides information concerning the location of data and the file system the host is viewing.